How Far Into Pregnancy Can You Tell the Gender?

Most parents start to wonder if their baby is a boy or a girl almost as soon as the pregnancy test turns positive. For some, playing the guessing game is half the fun of being pregnant. For others, having to wait to determine the baby's gender is incredibly frustrating. And although well-meaning friends may pass along a few old wives' tales about the baby's gender, the only foolproof determination is through invasive measures or a blood test.

Chorionic Villus Sampling

One of the earliest ways to determine the gender of the baby is through chorionic villus sampling 3. This is done between the 10th and 13th weeks of pregnancy, or near the end of the third month. Because of the risks involved -- the procedure can trigger miscarriage or cause minor birth defects -- this method is not solely used to determine gender but rather to identify potential chromosomal problems. During the procedure, a tiny sample of the the chorionic villi is taken from the placenta. The sample is analyzed for genetic information, including the baby's gender.


Amniocentesis is performed between weeks 15 and 20 4. In this procedure, a sample of the amniotic fluid, which contains fetal cells, is taken and analyzed. Amniocentesis is considered safer than chorionic villus sampling, but it does pose a small risk to the baby, so the procedure is usually only performed for purposes of genetic evaluation and chromosome analysis 34. In most cases, only women who have a high risk of having a baby with a chromosomal abnormality undergo the procedure.


Prenatal ultrasounds use sound waves to create an image of the baby. They are considered safe and are usually done around the 20th week of pregnancy. Birth defects and abnormalities can easily be seen on ultrasounds, as well as organs that identify the baby's gender. Usually, the gender can be seen by the 20th week. In general, the earlier the ultrasound is performed, the harder it is to accurately determine the baby's gender.

Blood Test

The MaterniT21 PLUS test was developed as a way to check for chromosomal abnormalities without using invasive measures. At the time of publication, it is only offered to expectant women in high-risk categories, including women over the age of 35, women who have a history of chromosomal abnormalities and those who have had abnormal ultrasounds or other screenings. The simple blood test can be performed as early as the 10th week of pregnancy. Along with information about Down syndrome and other chromosomal abnormalities, the test call also tell with great accuracy whether the baby is a girl or a boy.